CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE AND CYLINDER AIR EXCESSIVE RATE ESTIMATING DEVICE

摘要

PROBLEM TO BE SOLVED: To make NOx surely reducible by accurately and simply estimating a cylinder air excessive rate so as to recirculate exhaust gas as much as possible while stable lean operation can be performed without a misfire of an engine. SOLUTION: In a control device for an internal combustion engine provided in a vehicle which can perform lean operation by air/fuel ratio leaner than theoretical air/fuel ratio by providing an exhaust gas recirculation device, this constitution is provided such that a cylinder air excessive rate estimation means 23 estimates a cylinder air excessive rate based on an exhaust gas amount recirculated by the exhaust gas recirculation device and exhaust gas air/fuel ratio estimated from air/fuel ratio at steady operation time, and an exhaust gas recirculation amount control means 24 controls an exhaust gas amount recirculated by the exhaust gas recirculation device based on the cylinder air excessive rate estimated by the cylinder air excessive rate estimation means 23.